The use and/or control of light energy is important in many dental procedures, particularly those in which photo-curing adhesives, sealants and dental restorative materials are used. Photo-curing materials preferably cure when exposed to light having a selected wavelength or wavelengths, typically in the visible spectrum.
Photo-curable dental materials are a convenience to the dentist because the curing process can be initiated when desired. For example, a dental filling may be placed in a tooth cavity in contact with a photo-curable dental adhesive and manipulated as needed until the dentist is satisfied that the filling is oriented in its proper position. A source of light including the selected wavelength or wavelengths is then activated to initiate polymerization of the adhesive and securely fix the filling in place. Even in those dental procedures in which photo-curing dental materials are not used, the delivery and control of light is important to allow dental personnel to view the procedures being performed.
Conventional methods of providing reflective optical surfaces in connection with dental articles typically include the use of metal or substrates coated with thin layers of metals. Forming the dental articles including reflective optical surfaces completely of metal is typically expensive and may also suffer from other disadvantages such as increased weight, etc. Metal-coated optical surfaces are typically plastic or other substrates coated with a reflective metallic layer by, e.g., vacuum, vapor or chemical deposition. These coatings suffer from a number of problems including chipping or flaking of the metallic coating, as well as corrosion of the metallic layer.
These problems are exacerbated in many dental applications because the dental articles, including the optical surfaces, that are used in multiple procedures must typically be sterilized between procedures. Sterilization subjects the articles to heat and humidity that can increased the rate of degradation of the optical surfaces. For those dental articles including optical surfaces that may only be metal-coated, the problems of degradation can be even more severe when subjected to sterilization. In many cases, the dental articles including metal-coated optical surfaces may be disposed of after a single use which can increase the cost of the procedures in which those dental articles are used.
When used in connection with photo-curing dental restoratives, another disadvantage of many of the optical surfaces of dental articles includes their inability to selectively reflect or transmit desired wavelengths of light. Many photo-curing dental materials are activated or cured by light in a relatively narrow range of wavelengths, typically in the visible spectrum. Known optical surfaces of dental articles, however, are typically opaque (i.e., they reflect and/or absorb incident light) or they are transmissive for the visible spectrum, thereby preventing or making it difficult to observe the photo-curing dental materials during use without delivering at least some light in the photo-curing wavelengths. As a result, the need to observe the working area can cause at least some photo-curing of the dental materials.
In addition to the above considerations, dental articles often include optical surfaces that are not planar in shape, i.e., the optical surfaces are in the shape of simple or complex curves. Examples include a dental mirror with an optical surface in the shape of a convex surface, a light guide used in connection with the delivery of photo-curing light that employs a curved reflective tube to deliver light from a source to a location within a patient's mouth, etc.